Original Title: Opur, ou la conqûete de la rosée. Dew is a source of pure water, modest, generally, but which can prove to be an essential contribution in the places where water is missing mostly: deserts. Many hot countries suffer from the absence of water. However, its amount in the atmosphere can be considerable. The OPUR association was founded in 1999 to explore and develop inexpensive and practical alternative water sources and to unite both individuals and organizations interested in achieving these goals. OPUR is not a purely scientific organization but represent a wide cross-section of interests from the layman to the scientist. This documentary devoted to the OPUR projects in different arid countries relating to dew collection as the alternative source of water.